Search Publications
Untangling the Galaxy. I. Local Structure and Star Formation History of the Milky Way
Kounkel, Marina; Covey, Kevin
Gaia DR2 provides unprecedented precision in measurements of the distance and kinematics of stars in the solar neighborhood. Through applying unsupervised machine learning on DR2's 5D data set (3D position + 2D velocity), we identify a number of clusters, associations, and comoving groups within 1 kpc and | b| < 30^\circ (many of which have not…
Occurrence Rates of Planets Orbiting FGK Stars: Combining Kepler DR25, Gaia DR2, and Bayesian Inference
Ford, Eric B.; Ragozzine, Darin; Hsu, Danley C. +1 more
We characterize the occurrence rate of planets, ranging in size from 0.5 to 16 R ⊕, orbiting FGK stars with orbital periods from 0.5 to 500 days. Our analysis is based on results from the “DR25” catalog of planet candidates produced by NASA’s Kepler mission and stellar radii from Gaia “DR2.” We incorporate additional Kepler data product…
The Solar Neighborhood. XLV. The Stellar Multiplicity Rate of M Dwarfs Within 25 pc
Henry, Todd J.; Winters, Jennifer G.; Jao, Wei-Chun +6 more
We present results of the largest, most comprehensive study ever done of the stellar multiplicity of the most common stars in the Galaxy, the red dwarfs. We have conducted an all-sky volume-limited survey for stellar companions to 1120 M dwarf primaries known to lie within 25 pc of the Sun via trigonometric parallaxes. In addition to a comprehensi…
The Hubble Space Telescope PanCET Program: Exospheric Mg II and Fe II in the Near-ultraviolet Transmission Spectrum of WASP-121b Using Jitter Decorrelation
Nikolov, Nikolay; Mikal-Evans, Thomas; Sing, David K. +18 more
We present Hubble Space Telescope (HST) near-ultraviolet (NUV) transits of the hot Jupiter WASP-121b, acquired as part of the PanCET program. Time-series spectra during two transit events were used to measure the transmission spectra between 2280 and 3070 Å at a resolution of 30,000. Using HST data from 61 Space Telescope Imaging Spectrograph visi…
Kepler Planet Occurrence Rates for Mid-type M Dwarfs as a Function of Spectral Type
Muirhead, Philip S.; Cushing, Michael C.; Christiansen, Jessie L. +1 more
Previous studies of planet occurrence rates largely relied on photometric stellar characterizations. In this paper, we present planet occurrence rates for mid-type M dwarfs using spectroscopy, parallaxes, and photometry to determine stellar characteristics. Our spectroscopic observations have allowed us to constrain spectral type, temperatures, an…
An Excess of Jupiter Analogs in Super-Earth Systems
Lee, Eve J.; Knutson, Heather A.; Batygin, Konstantin +4 more
We use radial velocity (RV) observations to search for long-period gas giant companions in systems hosting inner super-Earth (1-4 R ⊕, 1-10 M ⊕) planets to constrain formation and migration scenarios for this population. We consistently refit published RV data sets for 65 stars and find nine systems with statistically signifi…
Precise Dynamical Masses of Directly Imaged Companions from Relative Astrometry, Radial Velocities, and Hipparcos-Gaia DR2 Accelerations
Dupuy, Trent J.; Bowler, Brendan P.; Brandt, Timothy D.
We measure dynamical masses for five objects—three ultracool dwarfs, one low-mass star, and one white dwarf—by fitting orbits to a combination of the Hipparcos-Gaia Catalog of Accelerations, literature radial velocities, and relative astrometry. Our approach provides precise masses without any assumptions about the primary star, even though the ob…
Two New HATNet Hot Jupiters around A Stars and the First Glimpse at the Occurrence Rate of Hot Jupiters from TESS
Latham, David W.; Narita, N.; Cochran, W. D. +68 more
Wide-field surveys for transiting planets are well suited to searching diverse stellar populations, enabling a better understanding of the link between the properties of planets and their parent stars. We report the discovery of HAT-P-69 b (TOI 625.01) and HAT-P-70 b (TOI 624.01), two new hot Jupiters around A stars from the Hungarian-made Automat…
The L 98-59 System: Three Transiting, Terrestrial-size Planets Orbiting a Nearby M Dwarf
Kostov, Veselin B.; Barclay, Thomas; Moran, Sarah E. +112 more
We report the Transiting Exoplanet Survey Satellite (TESS) discovery of three terrestrial-size planets transiting L 98-59 (TOI-175, TIC 307210830)—a bright M dwarf at a distance of 10.6 pc. Using the Gaia-measured distance and broadband photometry, we find that the host star is an M3 dwarf. Combined with the TESS transits from three sectors, the c…
Close Companions around Young Stars
Bizyaev, Dmitry; Oravetz, Daniel; Pan, Kaike +26 more
Multiplicity is a fundamental property that is set early during stellar lifetimes, and it is a stringent probe of the physics of star formation. The distribution of close companions around young stars is still poorly constrained by observations. We present an analysis of stellar multiplicity derived from Apache Point Observatory Galactic Evolution…